katalyst-core

The LinkML module every Katalyst schema module imports (src/katalyst_core/schema/katalyst_core.yaml):

• Node: the base node. Identity (id, a URI under a declared prefix; core itself is https://w3id.org/katalyst/core/, prefix kc:), kind, name, description.
• Lifecycle: lifecycle_state with a retired state, which is the default delete.
• Provenance: source, activity, derived_from.
• Two times: valid time (valid_from/valid_to) and recorded time (recorded_from/recorded_to).
• Relation: a reified relationship (subject, predicate, object) with a confidence and its own provenance and times.
• The extension bag (extensions): data no loaded module defines, kept and never deleted.
• DeletePolicy (block, cascade, detach, redirect): every relationship slot carries one as its delete_policy annotation.
• parent: the structural parent edge (child_of). A class lists it under slots: and names its parent kinds under slot_usage: parent:. No module defines parent again; one that does is refused when it loads.

A module imports it as katalyst_core:

imports:
  - linkml:types
  - katalyst_core

The Python package defines no schema. It opens modules (open_module), holds them to the core contract (contract.check_contract, kata core check), and moves records between YAML and RDF (graph.to_graph / graph.from_graph, kata core save / kata core load).

Lint the schema with the LinkML linter: just core-lint. The full linkml toolchain is a runtime dependency, so validation and linting are available wherever core is.